‘NCPUR06-020’ is a purple-fleshed sweetpotato with high levels of anthocyanin pigments in its storage roots. ‘NCPUR06-020’ was developed using conventional crossing and breeding methods. It is the first purple-fleshed variety in our industrial-type breeding populations to be released and it is intended for use in the natural colorant industry. Most colorants are synthetic and obtained from a wide variety of organic and inorganic sources. Natural and synthetic coloring additives are widely used in the food, cosmetic and pharmaceutical industries to enhance the appearance of products. There has been a recent trend to replace the use of synthetic colorants in food products with natural food colorants that have beneficial health properties and the natural colorant sector is increasing globally. The storage roots of purple-fleshed sweetpotatoes produce several purplish red anthocyanins in large quantities. Anthocyanins are an attractive source of natural colorants because they also possess many beneficial human health properties including antioxidative radical-scavanging abilities, anti-mutagenic, anti-hypertensive, anti-hyperglycemic and hepatoprotective properties.
Using conventional breeding techniques and a diverse array of germplasm, the sweetpotato breeding program developed a population of high pigment value, purple-fleshed sweetpotatoes. These varieties are suitable for anthocyanin extraction, and they are better than the current lines available in the US as they have increased color yields and better disease resistance compared to the existing purple-fleshed sweetpotatoes in the US.
‘NCPUR06-020’ is the first purple-fleshed sweetpotato variety to be released by the North Carolina State University sweetpotato breeding program. Several purple-fleshed sweetpotato varieties are currently grown and subjected to extraction in Japan and China. As with many other sweetpotato products, China is the largest producer of purple-fleshed sweetpotatoes. We believe there is a significant market for a “Made in the USA” purple-fleshed sweetpotato derived colorant and expect the ‘NCPUR06-020’ variety to be the first in a series of new purple-fleshed sweetpotatoes to be developed and released by NC State University sweetpotato breeding program for the natural colorant and functional foods sectors.
Lineage. The Ipomoea batatas ‘NCPUR06-020’ variety originated from a conventional cross between Ipomoea batatas breeding lines BM85-42 (the female parent; not patented) and NC414 (the male parent; patented as ‘Stokes Purple’ (U.S. Plant Pat. No. 17,976)). Botanical seed was harvested from this and other purple sweetpotato lines planted in our winter greenhouse-crossing block between September of 2005 and February of 2006. The breeding line BM85-42 is a white-fleshed biomass line from the USDA Vegetable Lab sweetpotato breeding program. The breeding line NC414 was a line provided to the program by a local farmer, which was subsequently patented and named ‘Stokes Purple’ (Sizemore et al. 2007). Botanical seed from the BM85-42×NC414 cross were planted in a greenhouse located in Raleigh, N.C. on Feb. 8, 2006. Seedlings with storage roots were cut and evaluated for flesh color with purple-fleshed selections being planted in Clinton, N.C. on May 9, 2006 to increase for multiple plant cuttings. Five plant cuttings were taken Jul. 5, 2006 and planted in Kinston, N.C. on Jul. 6, 2006. The variety ‘NCPUR06-020’ was selected from a five hill plot Oct. 23, 2006 because of its combination of exceptional features. ‘NCPUR06-020’ was increased, evaluated, and advanced as the variety ‘NCPUR06-020’, with “06” referring to the year in which it was selected, and “020” indicating that this was the 20th purple selection made by the breeding program in 2006. It has been propagated asexually since this time.
Asexual Reproduction. Since its selection, Ipomoea batatas ‘NCPUR06-020’ has been asexually reproduced at by vegetative propagation of vine cuttings and/or cuttings from root sprouts. Vegetative propagation was done in Clinton N.C. for increase and field evaluation and tissue culture micropropagation and tissue culture propagation was done in Raleigh, N.C. Successively, there have been six cycles of vegetative propagation, one cycle of tissue culture micropropagation, and multiple vegetative propagation cycles to increase the plant population.
Asexual reproduction of ‘NCPUR06-020’ using these methods has shown that the unique features of the new variety are stable and the plant reproduces true to type in successive generations of asexual reproduction.